First let’s start with the issue. For about 1/2-2/3 the travel time of the pedal I feel no response from my vehicle then on the later bit I’m able to bring my vehicle to a stop. My first remedy was to see if I had air in the lines. I was unable to remove the air from the lines and was able to narrow it down to a faulty abs module(I had tried doing a module and manual bleed but to no avail) so I replaced it with a proportioning value. I still have a squishy pedal but now I was getting no air coming out of my lines. Then I replaced the master cylinder with an upgrade version(part number M630031) and this also did not fix my problem. Then I figured I should check the rear drum brakes and I found them to be loose and one of the wheel cylinders to be leaking. I adjusted my drums and replaced the leaking cylinder and since I was at the shop doing this I power bleed the system just to be sure I didn’t have any air still in the system. At this point there is no more electronics in the system it’s strictly mechanical and hydraulic and I have checked the entire systems on a lift for leaks from all brake hoses and there is none. So that just leaves my brake booster(which I don’t think should cause this issue) and the chance the master cylinder I bought was faulty. I have had a few techs other then myself look at this and have spend countless hours trying to fix this issue if anyone has had experience with a problem similar to this or thinks they may know a solutions please let me know. I can also answers any questions about my post if anyone has. Thank you for your help.

 

I have been dealing with the same exact issue with my 1996 C1500 for the past couple of years. No braking until 1/2 to 2/3 of the way to the floor. Sometimes my brake pedal will go to the floor and get stuck, usually shortly after cranking or if I am at a red light and stand on the brake pedal too hard for too long. I end up having to hook my toe under the pedal and pull it up from the floor to release the brakes. Thankfully the 1996 is a spare vehicle and I drive it about 400 miles a year these days, mostly just to crank it once a month or so.

I've replaced the master cylinder, checked all wheel cylinders, and bled quarts of fluid through the system. At this point the brake booster is about the only thing I have not replaced, and I plan to go ahead and replace it one day soon.

 

I ended up changing the brake booster and now the brakes work perfectly.

 

**UPDATE** For anyone wondering how to fix an issue like this I ended up changing the brake booster on my truck and now the brakes work 100%. Since most online sources indicated that the symptoms I was having was not brake booster related and how a faulty brake booster would act alot differently then I was seeing. If you are certain no more air is coming or in your system and there are no leaks and you are certain of your master cylinders performance no not rule out the brake booster.

 

Thanks for reporting back. I’ve got the same issue and have replaced about everything except the brake booster - because as you say, all the diagnostic lists point to something else. But that is the only thing still original to my brakes, so I’ll do it next.